When building complex category structure with number of categories far beyond 100, it become very inconvinient to navigate it. Enhancement can be something like 'filter by parent' or view when only current level of categories is displayed (equal to filter by max levels =1) and there is a new link on each category to set it as 'parent' and show nested categories. It'd be much easier to navigate rather than scrolling.

Also, it'd be beneficial to have 'add article' and 'category' buttons in category details page which would add article or category with parent set to current category. Currently selecting parent category requires you to scroll big list in a small window. I changed max-height for .chzn-results to 500px in chosen.css, but it still not very convinient.